radiation … · web viewgamma – sterilising single equipment x-rays – radiographs each have...

Radiography

DefinitionsRadiography – method of making photographic records of parts of the body using x-raysRadiology – science of the diagnosis and treatment of disease using x-rays and radiographsRadiograph - Processed film showing an image of an object that has been exposed to x-rays. 2 dimensional images made up black, grey, white shadows.

Radiation A flow of energy from a source (x-ray machine for example) 4 types of radiation Alpha – smoke alarms Beta – treating thyroid cancer Gamma – sterilising single equipment X-rays – radiographs Each have different weights, size and travel at different

speeds

What are x-rays? Energy (photons) that can pass through tissue Man called Röntgen discovered x-rays could penetrate human

tissue in 1895.

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Interaction of x-rays with tissues Atoms – basic building block of matter (cells, tissue) 3 things can happen when x-rays come into contact with tissue

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Electrons

Nucleus includes protons and neutrons

1. Absorption X-ray photon interacts with electrons in the tissue

atom

This electron is knocked out into the tissue and has

lots of energy, causing disruption of other atoms. It’s

this energy that causes tissue damage.

The atoms is now called an ion.

2. Transmission Photon passes through the atom and doesn’t affect an

electron or the nucleus.

No damage

3. Scatter Photon bounces off the atom, but gets forced away,

escapes tissues.

An unintended target could be exposed to the x-ray

beam / photons.

Dangers of radiation

X-rays cannot be seen felt or heard Can cause mild burn to leukaemia Radiation to reproductive organs can damage DNA of eggs or

sperm Unborn child – congenital abnormalities

Legal requirementsHealth & Safety Act 1974 Health and Safety at work act 1974 controls workplace health, safety

and welfare. It identifies that everyone is responsible for H&S. Employer is responsible for providing safe work environment,

providing safe equipment and training Employee responsibility - Obey health and safety policy, use

equipment safely and wear provided PPE. Be aware of others safety. Good role model, report any issues.

Electrical testing on Radiography equipment, how often is it done?

Employee training – what are you expected to do? Set up the radiographs and holders? Turn the machine on? Develop the radiograph? Mounting the radiograph? Change chemicals and clean the developing machine? QA checks?

COSHH – developer and fix, Waste disposal – developer, fix, lead foil, film packet Risk Assessment – using the processor

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Be aware of others safety – ask anyone not involved in taking the radiograph to step outside the room / controlled area during exposure

Do not press the button to expose a patient to ionizing radiation

Infection ControlHand Hygiene should be carried out – prior to handling radiograph films and holders after handling films and holders that have been used during the

exposure

PPE – gloves should be worn when decontaminating film packets / sensor platesFilm packets should be wiped with a detergent wipe, followed by a disinfectant wipe, which should then be disposed of in the correct waste stream. Once films have been decontaminated the film / sensor plate should then be placed on to a clean tissue and gloves should be removed and disposed of. Hand hygiene should be performed before the radiograph leaves the clinical area to be developed / placed in the scanner. When processing the film a clean pair of gloves should be used then disposed of correctly

Ionising Radiations Regulations 1999 Relate principally to the protection of workers and the public. Ensures patient protection by regulating the safety of

radiographic equipment Local rules – display in each controlled area 1. local rules relate to radiation protection and should be

displayed in each controlled area.2. information should include name of rps3. description of controlled area - area approximately 1.5 meters

around the x-ray machine, the patient and not in the direct path of the main x-ray beam

4. names of qualified staff and instructions of equipment5. contingency plans in event of accident or emergency

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6. name of legal person7. dose levels8. name and contact of rpa9. arrangements of personal dosimetery (worn if 100 intra oral or

50 extra oral films taken in a week) 10. Employees responsibilities

Important people under IRR1999Legal Person Takes the legal responsibility for implementing

the requirements of the regulationsRadiation Protection Supervisor

Is appointed by legal PersonEnsure compliance with the RegulationsMost likely to be the Dentist, Hygienist, Therapist or Appropriately trained Dental Nurse

Radiation Protection advisor

Appointed by legal personProvides advice on compliance with the Ionising Regulations to the legal personProvides advice regarding quality assurance

Employees duties

Do not knowingly expose unnecessary radiationExercise responsible care when using radiographyImmediately report to the legal person when there has been an accident, faulty equipment or over exposure

Ionising Radiation (medical exposure) Regulations 2000 Relates to protection of the patient

Important people IR(ME)R 2000Referrer The registered medical practitioner, dental practitioner

or other health professional who is legally entitled to refer a patient for radiographic examination – Dentist

Practitioner

The registered medical practitioner, dental practitioner or other health professional who is legally entitled to take responsibility for a patient’s exposure to ionising radiation

Operator The person who is legally entitled to carry out all or

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part of the practical aspects of the radiographic examination

Employer The legal person. Provides overall safety and ensures everyone complies. Provides policies and protocols

Radiation protection file legal person responsible for includes local rules x-ray and film processing procedures Need for dosemetres Named staff and responsibilities Accident contingency plans – brought about by the risk

assessment and featured in local rules. Keep record log of film stock, fixer and developer in radiation

protection file Quality assurance documents. QA is the grading of

radiographs taken by the operator.

Quality assurance The purpose of a good quality control system is to ensure operator and patient safety. It will help lower the risks of having to retake radiographs by implementing a Quality Assurance system that all operators and employees adhere to.

It is used to:1. Justify the necessity for taking radiographs2. ensure diagnostically acceptable films3. adequate processing4. viewing and correct filing5. reduce the need for retaking radiographs6. reduce exposure to patients and staff

Grades of radiographs are:1. At least 70% must be Grade 1 – excellent quality

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2. No more than 20% Grade 2 – diagnostically acceptable3. No more than 10% Grade 3 – diagnostically

unacceptable The grading must be carried out by the operator.

Safety Discuss controlled area Dose kept as low as reasonably practicable (ALARP) Justify need for radiograph Exposure only to patient – controlled area Use fast speed films (Digital or E/F for traditional films) Use collimators and rinn holders Stand 1.5 metres away from beam Lead lined walls Switch machinery off after each use Maintain equipment – servicing every 3 years Train staff and responsibility Quality assurance procedures Radiation monitoring badges worn at hip level if taking more

than 100 intra oral or 50 extra oral radiographs per week

Personal Dosimeters

A radiation dosimeter is a device that measures exposure to ionizing radiation

A person must wear a Personal Dosimeter if they are carrying out over 100 intra oral or 50 extra oral radiographs per week.

Sometimes practices ask employees to wear them as a matter of course because ionizing radiation is being used throughout the practice

They are replaced quarterly and any readings are recorded and kept on file

They should be worn at the hip area due to the possible dangers to the reproductive organs

Dosimeters should not be removed from the practice, left in direct sunlight and should not be left where they could be affected by scatter radiation when not being worn

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https://en.wikipedia.org/wiki/Ionizing_radiation

Equipment failure general guidance: Stop procedure Inform legal person/RPA (see below for more detail) Identify failure and rectify if possible or contact appropriate

contractor if required to repair Risk assessment completed and action taken if advised Inform HSE if required Report in log books

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X-ray interaction with non digital radiograph

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Black images

Produced when the x-ray beam passes

through tissue and reaches film. This

demonstrates that the film has been

‘sensitised’.

White Images

Occurs due to x-ray beam not

reaching film – stopped by solid

object. This demonstrates no

interaction with the film.

Uses of radiography in dentistry

This image shows retained roots This image shows endodontic work and a fractured root

This image shows a periapical abscess and caries

This image shows periodontal disease

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This image shows a mixed dentition and possible impaction. This will be used for orthodontics

Radiograph images Intra oral – inside the mouth Extra oral – outside the mouth

Non digital intra oral film Direct action. Emulsion is designed to interact with the beam

directly.

Types of intra oral images

Periapicals

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Bitewings

Waterproof wrapping – to protect from moisture and light.Pimple should face the x-ray tube

Lead foil – absorbs scatter radiation

Black paper – wrapped round film to protect from light and damageBlack stream waste, unless contaminatedFilm – silver crystals in emulsion produce black

images (where x-rays have hit the film)Black stream waste, unless contaminated

Occlusal

Intra oral X-ray unit

Aiming device

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Collimator

Intra oral x-ray unit quality assurance

Step wedge should be used at the start of the morning before radiographs are taken on patients. It can be used for both non digital and digital systems. This test is used to ensure the x-ray machines are working correctly prior to using on a patient. Placed over a film and exposed to x-rays, the thicker the wedge the whiter the image produced, this ensures that the x-ray machine and developing equipment are working correctly. Check for oil leaking, cracks on tubehead, electric shocks from unit, loose arm on unit, simply not working

Extra-oral films

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Indirect action film

The emulsion on the film is designed to interact with light not x-rays

Lower dose of x-rays hits cassette which makes intensifying screens light up

This light produces image on film Lower dose of x-rays to patient – image not as fine quality as

intra oral

Types of extra oral images

Orthopantomograph

Cephalometric

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Lateral Oblique

Extra oral x-ray unit

Quality assurance for non digital films correct speed of film E/F film has not been damaged film is not out of date step wedge test (all films)

Processing non digital films

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Lateral Oblique

Manual processing

manual processing carried out in a dark room requires solution tanks, thermometer, immersion heater,

timer, film hangers Developer. Interacts with the silver crystals on the film that

has been hit by x-rays (soft tissue). The developer turns these sensitised areas black.

Water rinsing will stop the developer working Fixer recognises the areas that have not been hit by x-rays

(un-sensitised crystals), washes the unused crystals off and turns them white.

Both should be disposed of in red stream waste tubs Solutions require changing 10-14 days Temperature affects developing exposed film packet is unwrapped and film clipped to hanger film is immersed in developer and agitate several times in the

solution to remove air bubbles for time stated in manufacturer’s instructions @20oC

residual developer is rinsed off in water for about 10 seconds film then immersed in fixer for time stated in manufacturer’s

instructions @20oC film washed in running water for 10-20 minutes film allowed to dry

Quality assurance for manual processing tanks are full

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correct temperature water tanks have fresh water no light ingress into the room

Automatic processing

carried out automatically by a machine a runner carries the film into each section for the appropriate

amount of time Advantages – time saving – dry film in under 5 minutes, no

need for dark room, controlled Disadvantages – maintenance essential, equipment

expensive, smaller machines cannot process extra-oral films.

Quality assurance for automatic processing tanks are replenished/full water tank has fresh water no light ingress into the box

Non Digital Film Storage Film deteriorates in time In a cool, dry place Kept away from x-ray beam Kept away from chemical fumes including mercury Within boxes placed on the edges to prevent pressure

problems Use oldest stock first

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Stock control Use oldest stock first- ‘First in first out’ Regularly check expiry dates Required under IRMER - to keep record log of film stock, fixer

and developer in radiation protection file

Digital Radiographs Photons converted to light once they hit the sensor produces direct images onto computer screen normal x-ray machines used (intra oral and extra oral) x-ray film is not used radiation dose not as long minimal risk of miss file due to digital system disadvantage are the expense of equipment and possible

legal issues attached with being able to alter the image

Two main types of digital machines used Solid state sensor plates

Sensor cable connected directly to computer , with instant imaging on PC

Small, thin, flat, rigid rectangular boxes, usually black coloured

Various sizes available Sensor plate not autoclavable, protective barrier required

Photostimulable phosphor storage plates

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Image plate used, not an instant image Image plate must be inserted into reader machine, then

scanned by a laser and relayed to the computer to achieve image

The image on the sensor plate is then erased and ready to be re-used

No sensor cables Plate can be inserted into barrier envelope for infection

control, not autoclavable

Digital Quality assurance Sensor Plates – checked for any damage to the plates or

cables (if applicable) prior to using. Is the reader on the computer working?

Scanner – check no errors showing

Film mounting

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Film Faults as per power pointToo pale Developer too cold, too dilute,

exhausted. Not left in developer long enoughExposure too short

Too dark Developer too hot, too concentrated.Left in developer too longExposure too long

Fogging Exhausted fixer Expired films Poor storage conditions – warm Faulty safe light / light leakage

Black marks Developer contamination on film before developing process has taken place

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White marksFixer contamination before the developing process has taken place

Partially blank Insufficient developer in manual processing tanks

Partially blank Incorrect aimingNot using aiming devicesIncorrect collimation

Lead foil imageFilm placed in the oral cavity backwards(traditional film only)

Dark lines Film bent before use. Damage to emulsion (traditional films)

Artifacts Jewellery not removed (nose ring)

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Blurred image Patient, machine, film movement

Double image Film used twice

Static electricity

Radiograph removed from packaging too fast

Black area (right)Light leakage

White marks (extra oral) Dust on intensifying screens

Make up, acne scarsFixer splashes

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